Tag: autism spectrum disorder

Significant White Matter Changes in Autism Revealed by MRI

Significant alterations in the brain’s white matter in adolescents with autism spectrum disorder (ASD). Credit: RSNA and researcher, Clara Weber

Using specialised MRI, researchers found significant changes in the microstructure of the brain’s white matter, especially in the corpus callosum in adolescents and young adults with autism spectrum disorder (ASD) compared to controls. This research will be presented next week at the annual meeting of the Radiological Society of North America (RSNA).

“One in 68 children in the U.S. is affected by ASD, but high variety in symptom manifestation and severity make it hard to recognise the condition early and monitor treatment response,” explained Clara Weber, postgraduate research fellow at Yale University School of Medicine. “We aim to find neuroimaging biomarkers that can potentially facilitate diagnosis and therapy planning.”

Researchers reviewed diffusion tensor imaging (DTI) brain scans from a large dataset of patients between the age of six months and 50 years. DTI is an MRI technique that measures connectivity in the brain by detecting how water moves along its white matter tracts. Water molecules diffuse differently through the brain, depending on the integrity, architecture and presence of barriers in tissue.

“If you think of gray matter as the computer, white matter is like the cables,” Weber said. “DTI helps us assess how connected and intact those cables are.”

For the study, clinical and DTI data from 583 patients from four existing studies of distinct patient populations were analysed: infants (median age 7 months), toddlers (median age 32 months), adolescents, and young adults.

“One of the strengths of our study is that we looked at a wide range of age groups, not just school-aged children,” Weber said.

To assess the influences of age and ASD diagnosis on white matter microstructure, the research team created fractional anisotropy, mean diffusivity and radial diffusivity maps using data from the four studies.

Fractional anisotropy is the extent water diffusion is restricted to just one direction. A value of zero means that diffusion is unrestricted in all directions, while one means that diffusion is unidirectional. Mean diffusivity is the overall mobility of water molecules, indicating how densely cells are packed together. Radial diffusivity is the extent water diffuses perpendicular to a white matter tract.

“When white matter integrity is disrupted, we see more water diffusing perpendicularly, which translates to a higher radial diffusivity,” Weber said.

The key finding of the analysis was reduced fractional anisotropy within the anterior/middle tracts of the corpus callosum in adolescent and young adult ASD patients compared to individuals in the control group. The corpus callosum is a thick bundle of nerve fibers that connects and allows the two sides of the brain to communicate. Corresponding increases in ASD-related mean diffusivity and radial diffusivity were found in young adults.

“In adolescents, we saw a significant influence of autism,” Weber said. “In adults, the effect was even more pronounced. Our results support the idea of impaired brain connectivity in autism, especially in tracts that connect both hemispheres.”

Compared to controls, no reduction in fractional anisotropy was seen in the same tracts in toddlers and infants with ASD.

The researchers hope the findings can help improve early diagnosis of ASD and provide potential objective biomarkers to monitor treatment response.

“We need to find more objective biomarkers for the disorder that can be applied in clinical practice,” Weber said.

Source: EurekAlert!

Low Vitamin D in Pregnancy Can Raise Autism Risk

Source: Anna Hecker on Unsplash

Low maternal vitamin D intake during pregnancy can affect the development of autism in the child along with various other factors, according to a new study from the University of Turku, Finland, and Columbia University, USA.

The study, published in the Biological Psychiatry journal, included 1558 cases of autism spectrum disorder (ASD) and an equal number of matched controls born in Finland between January 1987 and December 2004, followed up until December 2015. 

Maternal vitamin D deficiency during pregnancy was linked to a 44% increased risk of ASD in the offspring, compared to women with sufficient vitamin D. 

The result persisted even when accounting for maternal age, immigration, smoking, psychopathology, substance abuse, the gestational week of blood draw, season of blood collection, and gestational age.

“The results are significant for public health as vitamin D deficiency is readily preventable,” said first author, Professor Andre Sourander from the University of Turku.

In previous work, the researchers had shown that vitamin D deficiency is also associated with increasede ADHD risk in the offspring. The serum samples were collected before the national recommendation for vitamin D supplementation during pregnancy was introduced in Finland. The current recommendation for pregnant women is a daily supplement of 10 micrograms of vitamin D throughout the year.

“Vitamin D deficiency is a major global problem,” Prof Sourander remarked.

Source: University of Turku

Dopamine Involved in Both Autistic Behaviour and Motivation

Dopamine can help explain both autistic behaviours and men’s need for motivation or ‘passion’ in order to succeed compared to women’s ‘grit’, according to a new study.

Men – more often than women – need passion to succeed at things. At the same time, boys are diagnosed as being on the autism spectrum four times as often as girls. Both statistics may be related to dopamine, one of our body’s neurotransmitters.

“This is interesting. Research shows a more active dopamine system in most men” than in women, says Hermundur Sigmundsson, a professor at the Norwegian University of Science and Technology’s (NTNU) Department of Psychology.

He is behind a new study addressing gender differences in key motivating factors to excel in something. The study uses men’s and women’s differing activity in the dopamine system as an explanatory model. The study enrolled 917 participants aged 14 to 77, consisting of 502 women and 415 men.

“We looked at gender differences around passion, self-discipline and positive attitude,” said Prof Sigmundsson. The study refers to these qualities as passion, grit and mindset. The researchers also applied theories to possible links with dopamine levels. Dopamine, a neurotransmitter that is released in the brain, is linked to learning, attention and our ability to focus. It can contribute to a feeling of satisfaction.

Men generally secrete more dopamine, but it plays a far more complex role than simply being a ‘happy hormone’. Dopamine is linked to learning, attention and our ability to focus.Previous studies on Icelandic students have shown that men are more dependent on passion in order to succeed at something. This study confirms the earlier findings. In six out of eight test questions, men score higher on passion than women.

However, the association with dopamine levels has not been established previously.

“The fact that we’ve developed a test to measure passion for goal achievement means that we can now relate dopamine levels to passion and goal achievement,” explained Prof Sigmundsson.

Women, on the other hand, may have greater self-discipline – or grit – and be more conscientious, according to other studies. Their level of passion may not be as pronounced in general, but they are also able to use this to excel.

The results for the women, however, are somewhat more ambiguous than men’s need to have a passion for something, and this study found no such gender difference. Nor did the researchers find any difference between the sexes in terms of growth mindset.

Previous studies have associated the dopamine system with many different conditions, such as ADHD, psychoses, manias and Parkinson’s disease. However, it may also be related to a certain form of autistic behaviour.

Some individuals with autism may develop a deep interest in certain topics, something which others may find strange or even off putting. People on the autism spectrum can focus intensely on these topics or pursuits, at least for a while, and dopamine may play a role in this.

“Other research in neuroscience has shown hyperactivity in the dopamine system in individuals with autism, and boys make up four out of five children on the autism spectrum. This, and dopamine’s relationship to passion, might be a mechanism that helps to explain this behaviour,” concluded Prof Sigmundsson.

Source: Norwegian University of Science and Technology

Journal reference: 
Sigmundsson, H., et al. (2021) Passion, grit and mindset: Exploring gender differences. New Ideas in Psychology. doi.org/10.1016/j.newideapsych.2021.100878.

Epidurals Do Not Increase Autism Risk for Babies

A Canadian study showed that children born to mothers who used epidural analgesia during labour were not at increased risk of developing autism spectrum disorder (ASD).

Epidural analgesia is administered into the epidural space around the spinal cord, typically during labour. Besides easing pain and reducing the use of other analgesics, it has also been shown to lower cortisol levels, expedite the return of bowel function, decrease the incidence of PE and DVT in the postoperative period, and reduce hospital stays.

Epidural analgesia is used by 73% of pregnant women in the U.S. for pain during labour. Since the US incidence of ASD increased from 0.66% in 2002 to 1.85% in 2016, there have been more efforts to identify environmental factors that put children at risk, the researchers said.

Elizabeth Wall-Wieler, PhD, of the University of Manitoba in Winnipeg, and colleagues drew from population datasets and included vaginal deliveries of singleton babies born in Canada from 2005 to 2016, following children from birth up until 2019.

Of the more than 123 000 infants included in the study, approximately 38% were exposed to epidural analgesia during delivery, and about 80 000 had a sibling in the study cohort. The mean age of mothers was 28 years. The children’s median age at their first diagnosis of ASD was 4 years. Births with epidural analgesia were more likely to be nulliparous or involve other factors such as foetal distress.
About 2.1% of children exposed to epidural labour analgesia (ELA) later developed ASD, compared with 1.7% who were not exposed, the team reported. But after factor adjustments, the researchers found no association between epidural analgesia and childhood ASD risk, they wrote in JAMA Pediatrics.

“This finding is of clinical importance in the context of pregnant women and their obstetric and anesthesia care professionals who are considering ELA during labor,” Dr Wall-Wieler and colleagues noted.

The group’s results contrast with Qiu et al.’s recent study that found a 37% increased risk of autism in children whose mothers used epidural analgesia during their delivery. Their study did not account for key perinatal factors, such as induction of labor, labor dystocia, and foetal distress, and drew criticism from five medical societies for possible residual confounding.

Dr Wall-Wieler and colleagues said that ELA is “recognized as the most effective method of providing labor analgesia,” adding that future qualitative research should assess how their findings — as well as the prior ones — have altered the perceptions about the perceived risk of ASD in offspring among both pregnant women and healthcare providers.

In an accompanying editorial, Gillian Hanley, PhD, of the University of British Columbia in Vancouver, and colleagues said that given the concerns stemming from previous findings, “it thus comes with some relief that Wall-Wieler et al found no association when controlling for key maternal sociodemographic and perinatal factors.”

“Epidural labor analgesia is an extremely effective approach to obstetric analgesia,” Dr Hanley’s group noted. “We have a collective responsibility to understand whether it is a safe option that sets a healthy developmental pathway well into childhood.”

The researchers observed an association between ELA and autism risk before accounting for confounders; but after controlling for all maternal sociodemographic, pre-pregnancy, pregnancy and perinatal factors, there was no longer a correlation.

In an analysis of siblings, researchers again observed a null association after controlling for all confounders and family fixed effects. Siblings who were exposed to epidural analgesia had a 2% cumulative risk of developing autism, and unexposed siblings had a risk of 1.6%.

The accuracy of inpatient and outpatient diagnostic codes for ASD, as well as coding for ELA was acknowledged as a study limitation by the researchers, as well as a lack of data describing epidural analgesia drug doses.

Source: MedPage Today

Journal information: Wall-Wieler E, et al “Association of epidural labor analgesia with offspring risk of autism spectrum disorders” JAMA Pediatr 2021; DOI: 10.1001/jamapediatrics.2021.0376.